The achievement of optimal performance in energetic compositions requires close control over the proportions of the oxidizer, binder and powdered metallic fuel or other particulate solid matter included in the composition. The attainment of high specific impulse combined with safety, reliability and favorable mechanical properties can suffer if the proportions are off, or if the composition is nonuniform. The problem becomes particularly acute when the compositions are prepared at locations close to the point of use. Solid compositions are at a disadvantage when compared to liquid or slurry compositions since the latter are much easier to mix and do not require casting or curing. Sources of error are the metering of three or more feed rates to control the proportions of all components, and the need to make a uniform mixture from components which differ in density, viscosity and other properties which tend to inhibit uniform mixing or stability.